freeradius(8) on Linux
The text 4bd49adacdcb, as Debian 7 (Wheezy) shipped it.
Authentication, Authorization and Accounting server
Flags it lists
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-C -
-X -
-f -
-h -
-i -
-l -
-m -
-n -
-p -
-s -
-t -
-v -
-x